Mix butter with powdered sugar, then add biscuit, chocolate and hazelnuts, and in the end fanta that will hold it all together. In the end, I mix it with hands so it can get together. You can put it in refrigerator for an hour to harden a bit so you can model it the way you want. If left longer in refrigerator it hardens pretty much, so you should take it out about an hour before cutting. It can stay for days without going bad.